[sechole] Inline templates pass through unsafe strings

Inline templates do not sanitize the inline variables properly.

This has slipped through the cracks since the test is not actually using an unsafe string. If I change the test to include some unsafe characters it fails:

  public function testInlineTemplate() {
    // ...
    $element = array();
    $element['test'] = array(
      '#type' => 'inline_template',
      '#template' => 'test-with-context {{ lama }}',
      '#context' => array('lama' => '<script>alert(\'oops\');</script>'),
    );
    $this->assertEqual(drupal_render($element), 'test-with-context ' . String::checkPlain('<script>alert(\'oops\');</script>'));
    // ...